i don't think those count as chansung fics tbh. i'm lacking for long chansung fic, but here's some recs, sweet anon (please read the tags i like piss fic):

baby, be fair by Busybee, E, 5.7k https://archiveofourown.org/works/53365033
honeypot by haedeluna, E, 3K https://archiveofourown.org/works/38937420
call it even (call me babe) by haedeluna, T, 6k https://archiveofourown.org/works/43694868
work in progress by chocomelon, G, 10.7k https://archiveofourown.org/works/36972799
glass shatter, gums bleed by jislvt, E, 3k https://archiveofourown.org/works/52157512
you just, you just, you just got me started by gift, E, 6.5k https://archiveofourown.org/works/52242418
overnight by pietrotheclown, E, 2k https://archiveofourown.org/works/55689493
You're Everything a Big Bad Wolf Could Want by tomorrowisblue, E, 10k https://archiveofourown.org/works/40323564/chapters/101005425

also plugging my own fic: dream glow, E, 20.6k https://archiveofourown.org/works/54362542

good luck <3